Featured Research

from universities, journals, and other organizations

Males and females differ in specific brain structures

Date:

February 11, 2014

Source:

University of Cambridge

Summary:

Reviewing over 20 years of neuroscience research into sex differences in brain structure, researchers have conducted the first meta-analysis of the evidence. The team performed a quantitative review of the brain imaging literature testing overall sex differences in total and regional brain volumes. They found that males on average have larger total brain volumes than women (by 8 to 13 percent). Looking more closely, the researchers found differences in volume between the sexes were located in several regions. These included parts of the limbic system, and the language system.

Reviewing over 20 years of neuroscience research into sex differences in brain structure, a Cambridge University team has conducted the first meta-analysis of the evidence, published this week in the journal Neuroscience and Biobehavioral Reviews.

Related Articles

The team, led by doctoral candidate Amber Ruigrok and Professors John Suckling and Simon Baron-Cohen in the Department of Psychiatry, performed a quantitative review of the brain imaging literature testing overall sex differences in total and regional brain volumes. They searched all articles published between 1990 and 2013. A total of 126 articles were included in the study, covering brains from individuals as young as birth to 80 years old.

They found that males on average have larger total brain volumes than women (by 8-13%). On average, males had larger absolute volumes than females in the intracranial space (12%; >14,000 brains), total brain (11%; 2,523 brains), cerebrum (10%; 1,851 brains), grey matter (9%; 7,934 brains), white matter (13%; 7,515 brains), regions filled with cerebrospinal fluid (11.5%; 4,484 brains), and cerebellum (9%; 1,842 brains). Looking more closely, the researchers found differences in volume between the sexes were located in several regions. These included parts of the limbic system, and the language system.

Specifically, males on average had larger volumes and higher tissue densities in the left amygdala, hippocampus, insular cortex, putamen; higher densities in the right VI lobe of the cerebellum and in the left claustrum; and larger volumes in the bilateral anterior parahippocampal gyri, posterior cingulate gyri, precuneus, temporal poles, and cerebellum, areas in the left posterior and anterior cingulate gyri, and in the right amygdala, hippocampus, and putamen.

By contrast, females on average had higher density in the left frontal pole, and larger volumes in the right frontal pole, inferior and middle frontal gyri, pars triangularis, planum temporale/parietal operculum, anterior cingulate gyrus, insular cortex, and Heschl's gyrus; bilateral thalami and precuneus; the left parahippocampal gyrus, and lateral occipital cortex.

The results highlight an asymmetric effect of sex on the developing brain. Amber Ruigrok, who carried out the study as part of her PhD, said: "For the first time we can look across the vast literature and confirm that brain size and structure are different in males and females. We should no longer ignore sex in neuroscience research, especially when investigating psychiatric conditions that are more prevalent in either males or females."

Professor Suckling added: "The sex differences in the limbic system include areas often implicated in psychiatric conditions with biased sex ratios such as autism, schizophrenia, and depression. This new study may therefore help us understand not just typical sex differences but also sex-linked psychiatric conditions. It is important to note that we only investigated sex differences in brain structure, so we cannot infer anything about how this relates to behaviour or brain function. Integrating across different levels will be an important goal for future research."

Professor Baron-Cohen commented: "Although these very clear sex differences in brain structure may reflect an environmental or social factor, from other studies we know that biological influences are also important, including prenatal sex steroid hormones (such as fetal testosterone) as well as sex chromosome effects. Such influences need to be teased out, one by one."

Dr Meng-Chuan Lai, another member of the team, noted: "The advantage of conducting a meta-analysis is that we can summarise the best knowledge from a vast, heterogeneous literature, with a very large sample size. However, we found a bias in the existing literature towards the use of volunteers over 18 years old, probably because this is the easiest age group to recruit and to brain scan. We need more research exploring brain development over the entire lifespan, especially in the early, formative years."

More From ScienceDaily

More Mind & Brain News

Featured Research

Mar. 3, 2015 — Why do people shake hands? A new study suggests one of the reasons for this ancient custom may be to check out each other's odors. Even if we are not consciously aware of this, handshaking may ... full story

Mar. 3, 2015 — Doctors write millions of prescriptions a year for drugs to calm the behavior of people with Alzheimer’s disease and other types of dementia. But non-drug approaches actually work better, and carry ... full story

Mar. 3, 2015 — Briefly counseling college students on the dangers of binge drinking is effective in lowering heavy drinking levels among many students, but only temporarily. Three out of four will be right back ... full story

Mar. 3, 2015 — Loneliness brought about by the death of a spouse can trigger a wider network of depression-like symptoms, a study has found, but authors suggest that doctors are often too quick to attribute these ... full story

Mar. 3, 2015 — Family Based Interpersonal Psychotherapy (FB-IPT) is more effective in treating preadolescent children with depression compared to child-centered therapy (CCT), a recent study has found. ... full story

Mar. 3, 2015 — Everyone worries about losing their memory as they grow older—memory loss remains one of the most common complaints of the elderly. But the molecular reasons behind the processes remain unclear, ... full story

Mar. 3, 2015 — A strong link has been made between subthreshold manic episodes and likelihood of developing bipolar disorder in children of parents with bipolar disorder. The study’s findings could improve ... full story

Mar. 2, 2015 — A newly published study is the first to report an association between bisphenol-A (BPA), a common plasticizer used in a variety of consumer food and beverage containers, with autism spectrum disorder ... full story

Mar. 2, 2015 — On Feb. 26, a picture of a cocktail dress originally uploaded to the blog Tumblr swept the Internet and managed to divide the population over a simple question: What color is the dress? Some viewers ... full story

Mar. 2, 2015 — A deficiency in the protein responsible for moving glucose across the brain's protective blood-brain barrier appears to intensify the neurodegenerative effects of Alzheimer's disease, according to a ... full story

May 8, 2013 — Using MRI, neuroscientists have found significant differences in brain anatomy when comparing men and women with dyslexia to their non-dyslexic control groups. Their study is the first to directly ... full story

Feb. 19, 2013 — Male rat pups have more of a specific brain protein associated with language development than females, according to a new study. The study also found sex differences in the brain protein in a small ... full story

June 13, 2011 — The brains of all vertebrates display gender-related differences. In songbirds, for example, the size of the brain areas that control their singing behaviour could be linked to the size of their song ... full story

Oct. 27, 2010 — People love to speculate about differences between the sexes, and many brain imaging studies have reported sex differences in brain structure or activity. But we should be skeptical about such ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.